The present invention relates to fasteners and particularly to fasteners for attaching a panel to a support member.
There exists a variety of polymeric fasteners employed for attaching panels to support members as, for example, in the automotive industry where a vehicle interior trim panel is attached to a structural support which can be made of sheet metal, a polymeric material, composite materials or the like, which are used in the automotive industry for doors and other vehicle components covered by trim panels. In the past, a common problem with such panels has been that during assembly fasteners, which are typically attached to a trim panel, are difficult to align to apertures in the sheet metal, and there is insufficient lateral adjustment to allow proper alignment. As a result, misaligned fasteners sometimes result in a mallet being employed to attach, for example, a door panel to a vehicle door, which can fracture the polymeric fastener. Also, overstressing the fastener during assembly or use (i.e., shutting door) or due to misalignment or due to poor fastener design may cause the fastener to break or fatigue or otherwise result in a loss in retention strength for holding the trim panel in place. As a result, door trim panels frequently become loose because of improper fastener geometry or installation.
Many fasteners are of two-piece construction including a pin and a mounting grommet which allows a panel once installed to be removed and reattached by a separating joint between the pin and grommet. The trim panel itself includes a socket referred to as a xe2x80x9cdoghousexe2x80x9d which receives one end of the fastener. In the past, the strength of the doghouse interface with the panel has been less than that of the separating joint between the pin and grommet, resulting in the doghouse pulling from the substrate before the fastener separates, thereby preventing reinstallation of a vehicle panel once removed for servicing a door interior part.
Other problems exist, such as when fastener pins employing annular ridges are preseated into a mounting grommet before the mounting grommet is secured within one of the panels. The subsequent seating of the other end of the pin into the support structure is. prevented by the lower insertion force between the pin and grommet. Thus, instead of properly inserting the fastener into an underlying support member, the pin slides further within the grommet. Many fasteners currently employed also require a separate foam sealant surrounding the aperture in, for example, the sheet metal support structure to prevent moisture from seeping through the sheet metal hole onto the trim panel.
As a result of all the difficulties with existent polymeric fasteners for attaching, for example, vehicle interior trim panels to vehicle sheet metal and particularly door panels to the sheet metal structure of a door, warranty claims for loose panels and broken fasteners are one of the major concerns in the automotive interior trim field. There exists a need, therefore, for a fastening assembly which will allow secure attachment of a vehicle interior trim panel to supporting sheet metal and allow assembly line techniques with the proper alignment of the fasteners with both the trim panel and support member as well as allow the panel to be removed and reinstalled without damaging the trim panel or the fastener. Also, the fastener should maintain the panel securely in place during use including, for door panels, when a door is slammed shut.
The fastener of the present invention meets these needs by providing a mounting grommet which includes a funnel-shaped receiver communicating with an aperture for receiving one end of a fastener pin having a plurality of spaced annular ratcheting grooves formed thereon. The opposite or second end of the pin is pointed and includes at least one resilient locking arm for insertion into an aperture in the support structure. Interposed between the first and second ends of the fastening pin is a resilient, generally cup-shaped seal which engages a surface of the support structure opposite the locking arm for providing a seal surrounding the aperture in the support structure to which the fastening pin is inserted. In a preferred embodiment, a pair of locking arms extend divergently outwardly and away from an apex of the second end of the pin at an acute angle and at a spacing of about 180xc2x0 and terminate in ends which snap-fit to the edge of the aperture into which the pin is extended under the compressive force of the seal. In a preferred embodiment also, the grommet further includes an annular slot defined by a collar on one side and a shoulder of the funnel-shaped receiver on the other. The shoulder includes an outwardly extending, resilient, annular flange cooperating with the support structure secured to the trim panel for centering the grommet.
In one embodiment of the invention, a trim panel includes a support socket to receive the annular slot of the grommet and lock the grommet in place. The support socket is defined by a slotted aperture for receiving the shoulder of the grommet and at least one resilient locking arm extending to one edge of the aperture for engaging the edge of the collar of the grommet when entered into the aperture of the support socket to lock the grommet in place while allowing two dimensions of lateral adjustment for final alignment. The support socket includes reinforcing ribs surrounding the aperture and engaging the shoulder of the grommet such that the grommet, once locked in place, will tend to self-center in the aperture.
With the structure of the present invention, therefore, an improved fastening system is provided for attaching a panel to a support member or substrate and particularly a door trim panel to the underlying support structure of the door utilizing a unique, self-aligning dual-ended fastening pin which cooperates with an improved grommet structure for receiving one end of the pin and, in one preferred embodiment, an improved trim panel with support structure for receiving the grommet and allowing self-alignment of the grommet and pin with the support structure of the vehicle.